Image forming apparatus employing powder, ink or similar toners require maintenance to replenish the toner repeatedly. A cartridge-type toner container is used as the replacement component for simplifying this work. In addition, consumables containing the toner, such as a developer unit, a photoconductive drum and the like, are used by themselves or in combination. Such consumables employ an expendable toner cartridge or a cartridge which is to be refilled with the toner.
In the field of image formation using toner, with expanded use of and increased demand for printers, copiers, facsimiles, microfilm reader printers and the like, the public demands continued improvement in printing and image quality.
In this connection, the public has become aware that the quality of printing and image formation varies depending upon the quality of the replacement components when they are used. Accordingly, each component replacement involves adjustment to reduce or eliminate such variations in quality. This results from the variations in use characteristics of the replacement components. For instance, powder toner may have variable chargeability depending upon the production lot, resulting in variations in image density or fogged images. Similar problems of varied use characteristics arise in the use of other replacement components, with the result that predetermined operating conditions are not stably achieved on occasion. A user must depend upon a service engineer to perform adjustments beyond the capability of the user, resulting in increased work for the service engineers and increased cost for users. This is inconvenient for users because it takes a long time before the adjustment is done.